Field sequential display systems that have a field sequential display that displays a plurality of images on a time-division basis and a liquid crystal shutter eyeglass have been proposed and developed.
As field sequential display systems, for example three-dimensional display systems that allow the viewer to perceive three-dimensional images are known.
FIG. 1 is a schematic diagram exemplifying a three-dimensional display system. In FIG. 1, the three-dimensional display system includes liquid crystal display device 100 that is a field sequential display and liquid crystal shutter eyeglass 101. Liquid crystal shutter eyeglass 101 has a liquid crystal shutter 101a for right eye and a liquid crystal shutter 101b for left eye.
Liquid crystal display device 100 alternately displays images for the right eye and images for the left eye. Right-eye type liquid crystal shutter 101a and left-eye type liquid crystal shutter 101b individually change between a light transmitting state in which light is caused to be transmitted and a light shading state in which light is caused to be shaded in synchronization with images for right eye and images for left eye that are displayed. Thus, images for right eye enter the right eye of viewer 102, whereas images for the left eye enter the left eye of viewer 102. If images for the right eye and images for the left eye are images that cause a parallax on the right and left eyes, these images can cause the viewer to perceive three-dimensional images.
As field sequential display systems, multi-view display systems that cause a plurality of viewers to perceive different images are known. A multi-view display system is presented in Patent Literature 1. The structure of the multi-view display system is the same as that of the three-dimensional display system shown in FIG. 1.
In the multi-view display system, liquid crystal display device 100 successively displays images for a plurality of viewers. Liquid crystal shutter eyeglass 101 which each of the plurality of viewers wears changes between the light transmitting state and the light shading state in synchronization with images displayed for the viewers. As a result, the multi-view display system can cause a plurality of viewers to perceive different images.
FIG. 2 is a descriptive diagram exemplifying the operation of a multi-view display system. In FIG. 2, three viewers 102a to 102c respectively wear liquid crystal shutter eyeglass 101.
Liquid crystal display device 100 successively displays image A1, image B1, image C1, and image A2. Liquid crystal shutter eyeglass 101 of viewer 102a changes the light transmitting state when images A1 and A2 are displayed; liquid crystal shutter eyeglass 101 becomes the light shading state when other images are displayed. Thus, viewer 102a successively perceives images A1 and A2.
Likewise, liquid crystal shutter eyeglass 101 of viewer 102b changes the light transmitting state when image B1 is displayed; liquid crystal shutter eyeglass 101 changes the light shading state when other images are displayed. Likewise, liquid crystal shutter eyeglass 101 of viewer 102c changes the light transmitting state when image C1 is displayed; liquid crystal shutter eyeglass 101 changes the light shading state when other images are displayed. Thus, viewer 102b perceives image B1, whereas viewer 102c perceives image C1.
As a result, viewers 102a to 102c perceive different images.
As field sequential display systems, a secure display system that causes only viewers who wear a liquid crystal shutter eyeglass to perceive images is known. In the case of a display for a portable information terminal such as a note-type personal computer as a field sequential display, a secure display system can accomplish a highly secured portable information terminal.
FIG. 3 is a schematic diagram exemplifying a secured display system.
In FIG. 3, field sequential display 104 of portable information terminal 103 alternately displays images and their inverted images, for example, image A, inverted image A′ of image A, image B, inverted image B′ of image B.
In this case, since a viewer who does not wear liquid crystal shutter eyeglass 101 perceives an achromatic image of which an image and its inverted image have been integrated, he or she cannot perceive images A and B.
In contrast, when liquid crystal shutter eyeglass 101 changes the light transmitting state in synchronization with images A and B that are displayed and changes the light shading state in synchronization with inverted images A′ and B′ displayed, viewer 102 who wears liquid crystal shutter eyeglass 101 can perceive images A and B.
Thus, the secure display system can cause only viewers who wear liquid crystal shutter eyeglass 1 to perceive images A and B.
In the foregoing field sequential display system, a change occurred in the state of the liquid crystal shutter eyeglass changed between the light transmitting state and the light shading state in which not only display light emitted from the field sequential display, but also ambient light, except for display light, is emitted. Thus, as a problem that arises, the viewer senses flickering caused by ambient light. In particular, if ambient light contains light emitted from a light source such as a fluorescent lamp that instantaneously flickers, since the period in which a change occur in the state of the liquid crystal shutter eyeglass, between the light transmitting state and the light shading state, deviates from the period in which ignition of the light source occurs, flickering that the viewer senses becomes large.
As techniques that reduce flickering caused by ambient light, a three-dimensional image recognition device, as presented in Patent Literature 2, and a three-dimensional image display device, as presented in Patent Literature 3, are known.
The three-dimensional image recognition device presented in Patent Literature 2 is provided with a CRT and a liquid crystal shutter eyeglass. Provided on the display screen of the CRT is a linearly polarizing filter. Moreover, in the liquid crystal shutter eyeglass, a liquid-crystal-injected glass plate into which liquid crystal has been injected, and a linearly polarizing filter are stacked such that the liquid-crystal-injected glass plate faces the CRT.
In the foregoing three-dimensional image recognition device, since the display light emitted from the CRT becomes polarized light, when the orientation of the polarized light that is transmitted through the liquid crystal that has been injected in the liquid-crystal-injected glass plate is changed, a change can occur in the state of the display light between the light transmitting state and the light shading state. In contrast, since ambient light is not polarized light, even if display light is shaded by the liquid crystal shutter eyeglass, ambient light is not shaded. Thus, since ambient light always transmits through the liquid crystal shutter eyeglass, flickering caused by the ambient light can be reduced.
The three-dimensional image display device presented in Patent Literature 3 is provided with a color picture tube and a polarizing eyeglass. Formed on the display screen of the color picture tube is a liquid crystal layer.
In the foregoing three-dimensional image display device, when the orientation of the polarized light of the display light emitted that is from the color picture tube is changed by the liquid crystal layer, a change can occur in the state of the polarizing eyeglass between the light transmitting state and the light shading state of the display light. In this three-dimensional image display device, like the three-dimensional image recognition device presented in Patent Literature 2, since the ambient light is not shaded by the liquid crystal shutter eyeglass, flickering caused by the ambient light can be reduced.
Besides the techniques presented in Patent Literatures 2 and 3, it can be contemplated that when part of the lens section of the liquid crystal shutter eyeglass is a liquid crystal shutter, flickering that the viewer senses will be reduced.
FIG. 4A is a side view showing a liquid crystal shutter eyeglass in which part of the lens section is a liquid crystal shutter; FIG. 4B is a descriptive diagram showing that a viewer who wears the liquid crystal shutter eyeglass shown in FIG. 4A is viewing a field sequential display.
As shown in FIG. 4A, lens section 200 of the liquid crystal shutter eyeglass is supported by frame 201. In addition, formed in lens section 200 is liquid crystal shutter 202 that has a diameter smaller than the lens diameter. Moreover, liquid crystal shutter 202 is composed of liquid crystal cell 203 and a pair of polarizing layers 204 that sandwich liquid crystal cell 203.
As shown in FIG. 4B, viewer 210 views field sequential display 212 with visual field range 211A. At this point, when display light emitted from field sequential display 212 enters liquid crystal shutter 202, since a change occurs in the state between the light transmitting state and the light shading state, display light 221 that lies in the light transmitting state changes to the light shading state.
Now, it is assumed that ambient light 222 that is emitted from fluorescent lamp 213 or the like enters the eyes of viewer 210 from peripheral visual field range 211B of visual field range 211A of the viewer but does not pass through liquid crystal shutter 202 in lens section 200. In this case, since no change occurs in liquid crystal shutter 202 between the light transmitting state and the light shading state of ambient light 222, flickering that viewer 210 senses can be reduced.
Liquid crystal shutter eyeglasses in which part of the lens section is a liquid crystal shutter and the related techniques are presented in Patent Literatures 4 to 11.